In the known art the desired shape is commonly imparted to fabric wig foundations by local folding and tucking. This results in small but definite local differences in the number of fabric layers and hence the thickness of the wig or hair-piece foundation. Shape conformity achievable with this construction is also not geometrically ideal. Smoother shape conformity has occasionally been obtained with a thick net fabric sometimes known as "vegetable net" by impregnating with water-soluble materials (e.g. starch) and wetting at the time of shaping on a wooden block. Apart from the coarseness of foundations so made the degree of conformity achievable in this way is comparatively low, the effect is not permanent and practicable shapes are confined to limited areas of low curvature.
It is desirable that, consistent with the required strength and hair-anchoring properties, the fabric of a wig foundation should be as fine as possible and offer the least obstruction to light, so as not to be noticeable against the scalp. This effect may be improved still further by suitable colouring of the fabric. In hair-pieces and wigs produced by the anchoring of hairs to the fabric of the foundation, the fabric should be fairly open, with a mesh size suitable for the anchoring process used, and filament strength high enough to stand up to the stresses imposed during hair-attaching operations and to those encountered in normal service. In most good-quality products that process will consist in knotting-in of the hairs; an example of a suitable mesh size for the fabric of the foundation is from 0.5 and 1 mm.sup.2.